Positron cooling and annihilation in room temperature noble gases is simulated using accurate scattering and annihilation cross sections calculated with many-body theory, enabling the first simultaneous probing of the energy dependence of the scattering and annihilation cross sections. A strikingly small fraction of positrons is shown to survive to thermalization: $\sim 0.1$ in He, $\sim 0$ in Ne, $\sim 0.15$ in Ar, $\sim 0.05$ in Kr, and $\sim 0.01$ in Xe. For Xe, the time-varying annihilation rate ${\overline{Z}}_{\text{eff}}(\tau )$ is shown to be highly sensitive to the depletion of the momentum distribution due to annihilation, conclusively explaining the long-standing discrepancy between gas-cell and trap-based measurements. Overall, the use of the accurate atomic data gives ${\overline{Z}}_{\text{eff}}(\tau )$ in close agreement with experiment for all noble gases except Ne, the experiment for which is proffered to have suffered from incomplete knowledge of the fraction of positrons surviving to thermalization and/or the presence of impurities.

中文翻译：

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稀有气体中的正电子冷却和An灭

使用多体理论计算的精确散射和an灭横截面，可以模拟室温稀有气体中的正电子冷却和an灭，从而可以同时探测散射和an灭横截面的能量依赖性。事实表明，极少的正电子可以幸存下来进行热化处理：$〜0.1$ 在他里面 $〜0$ 在Ne， $〜0.15$ 在Ar， $〜0.05$ 在Kr中，以及 $〜0.01$在Xe中。对于Xe，随时间的an灭率${\overline{ž}}_{\text{效}}（\tau ）$结果表明，由于to灭，它对动量分布的损耗高度敏感，从而最终解释了气室测量与基于阱的测量之间长期存在的差异。总体而言，使用准确的原子数据可以得出${\overline{ž}}_{\text{效}}（\tau ）$ 与除Ne以外的所有稀有气体的实验都非常吻合，对于该稀有气体，实验证明其对幸存于热中的正电子比例和/或存在杂质的知识不完全。